1. Field of Invention
This invention relates to a rotation-inducing device. More specifically, it is directed to a device that provides rotation of a lower portion relative to a nonrotating upper portion and that provides subterranean operation or operation in another similar remote location. An example of an operation in a similar remote location includes removing blockage in a pipe having discrete access sites.
Many subterranean applications utilize a surface communication apparatus that cannot rotate and, thereby, provide rotation at the remote subterranean location. Illustrative of such nonrotating surface communication apparatus is a coil tubing commonly used in the oil recovery industry.
However, a number of applications, such as coil tubing fishing operations, alignment of directional coil tubing drilling operations, down-hole impact hammer applications, and pipe line cleaning operations, either require rotation at the remote location or would be enhanced thereby. For clarity and ease of description, the remainder of this application shall use the above-mentioned example of a coil tubing fishing operation to describe the present invention.
Often during drilling, the drilling string breaks leaving the "tool string" at the bottom of the hole. This lost tool string is commonly referred to as the "fish." In a coil tubing fishing operation, a coil tubing, having a "fishing string" thereon, extends through a production tubing to connect the fish. The fishing string includes a connector, such as an overshot or a spear, to accomplish the attachment of the fishing string to the fish.
An overshot utilizes rotational cutters for creating external threads similar to a die. Likewise, a spear uses rotational cutters for creating internal threads similar to a tap. When forced against the fish and rotated, the overshot (or spear) cuts threads onto the fish and, thereby, connects to the fish.
Presently, a majority of subterranean operations employ a hydraulic motor to accomplish the rotation of the lower portion, such as an overshot. However, the motors are difficult to control often causing damage to the well; the motors require hydraulic power fluid which often impairs the operation; and the motors prohibit the use of a hydraulic disconnect downstream of the motors which often results in the loss of the motors during a failed fishing attempt.
Because of the disadvantages of hydraulic motors in rotating a lower portion, such as an overshot, a purely mechanical rotation device that does not require hydraulic power fluid, that facilitates accurate rotational control, and that allows for use of a hydraulic disconnect below the rotating device is desired for subterranean applications.
2. Related Art
U.S. Pat. Nos. 5,224,547 and 5,310,001 that issued to Burns Sr. et al. disclose a retrieving tool for downhole packers utilizing non-rotational work strings and a method for accomplishing same. The apparatus disclosed by Burns utilizes mating mandrels including J-slots to facilitate rotation of the lower portion. The J-slot design translates relative axial motion of the power mandrel and inner mandrel into relative rotational motion of same. However, because of the J-slot design, the inner mandrel rotates only a fraction of a 360 degree revolution per axial stroke of the power mandrel. Consequently, the power mandrel must complete a number of axial strokes, or cycles, to produce a single 360 degree revolution of the inner mandrel. In addition, the Burns reference does not provide for the use of a hydraulic disconnect below the apparatus. Further, the Burns reference does not provide a sealed environment that will permit the transmission of a pressurized fluid therethrough.
Though the above mentioned rotation devices may be helpful in providing down-hole or remote rotation, they can be improved to provide more efficient and accurate rotation, to allow for use of a hydraulic disconnect below the device, and to provide a sealed environment that permits transmission of a pressurized fluid therethrough.